1. Field of the Invention
The present invention relates to a vehicle provided with an engine and the engine, more particularly to a vehicle provided with an engine including an oil circulation route having an oil pan in a lower end of a transmission chamber of a crank case, and the engine.
2. Description of the Prior Art
One example of the oil circulation route in the vehicle engine having the oil pan in the lower end of the transmission chamber will be briefly described. Oil suctioned from the oil pan by an oil pump is supplied to oil feeding points of the engine such as a bearing of a crankshaft, a crank pin, a piston, a clutch, a generator, a cam shaft of a cylinder head, and a transmission shaft via oil passages for oil supply and then utilized for lubrication and/or cooling at the oil feeding points. The supplied (used) oil is returned to the oil pan of the transmission chamber via oil passages for oil return of the points, a crank chamber, a clutch chamber or a generator chamber and the like. Such an oil circulation route is described, for example, in Japanese Unexamined Patent Publication No. 2006-105132.
In order to suction the oil without air entrainment by the oil pump at the time of driving the vehicle so as to properly supply the oil to the feeding points, there is a need for always leaving the oil in the oil pan within a range of a predetermined oil level. Therefore, there is a conventional engine provided with a scavenging pump in the engine separately from the oil pump. That is, the oil returning from the oil feeding points to the crank chamber, the generator chamber, the clutch chamber and the like is forcibly pumped up by the scavenging pump and returned to the oil pan of the transmission chamber. However, in a case where the scavenging pump is provided, the number of parts and cost are increased. Since the scavenging pump is driven by utilizing rotation of the crankshaft of the engine, an output of the engine is also decreased.
Meanwhile, in a case where the scavenging pump is not provided, the cost of parts can be reduced and there is no loss in the output of the engine. However, depending on a driving situation of the vehicle, for example when the vehicle is inclined forward, rearward, leftward or rightward at the time of driving on a slope or the like, there is sometimes a case where an oil amount in the oil pan becomes insufficient due to movement of the oil in the oil pan, or too much oil is gathered in a chamber other than the oil pan.